Bronze chain plates

[scherzoja]

Benz: I'm putting them on my Pearson 367. Shrouds were internal, I moved them a few inches outboard to external. Backstay was external and remains external. The headstay chain plate is integrated with the anchor platform (that's stainless). I'll post pics in a few months once they are installed with internal reinforcements.

AlaskaViking: Sheet metal shops around here couldn't bend 3/8" x 2" flat bar, so I took the metal to a machine shop. I needed two different machine shops. One to cut and bend, the other one to cut square holes.

None of the six machine shops I contacted could do the entire job.

To be more specific, B & S Machine shop did the square holes (https://www.bsmachineshop.com)

Escambia Fabrication did the cutting/bending (https://www.facebook.com/pages/categ...9266603712503/)

[alaskanviking]

Originally Posted by scherzoja

Benz: I'm putting them on my Pearson 367. Shrouds were internal, I moved them a few inches outboard to external. Backstay was external and remains external. The headstay chain plate is integrated with the anchor platform (that's stainless). I'll post pics in a few months once they are installed with internal reinforcements.



AlaskaViking: Sheet metal shops around here couldn't bend 3/8" x 2" flat bar, so I took the metal to a machine shop. I needed two different machine shops. One to cut and bend, the other one to cut square holes.



None of the six machine shops I contacted could do the entire job.



To be more specific, B & S Machine shop did the square holes (https://www.bsmachineshop.com)



Escambia Fabrication did the cutting/bending (https://www.facebook.com/pages/categ...9266603712503/)

Thank you! That puts me on a path forward.

So you ordered the bronze

Took it to a shop to cut and bend the sheet

Took them to another shop to cut/punch the square holes

Then you ground the end round, drilled the pin hole, and sanded/polished yourself.

Your plates are fairly similar to mine. How much did the bronze/bending/punching cost?

I was thinking of sending them to get chromed after. More corrosion resistance, and the turnbuckles are chromed bronze.

[scherzoja]

Yes, you understood the sequence correctly. You might get lucky and find one shop that can cut, bend, and cut square holes.

I compared the price of carriage bolts vs hex bolts and the price difference was not that much greater or carriage bolts (about a $4 difference).

If you don't want carriage bolts, the bronze is easy to drill. Much easier than stainless. I had a problem with my bits grabbing into the bronze and jamming (sharp cobalt bit), which caused the chuck to spin in the drill press (Morse taper chuck). I used a not-too-sharp steel bit to remove the bite marks. Once the bit grabbed, I just switched to a steel bit and finished the hole.

I also used Skene's table to calculate the location of the center for the clevis pin hole. It's not the center of the radius. There is a vertical offset that moves the hold center down a bit. See attached image. I also attached my drawing of the lower shroud chain plates to illustrate the offset. All my chain plates are 3/8" because I didn't want to buy different thicknesses of plate, so I made them all as thick as the backstay.


Bronze plate: $630 (incl shipping)
Cut and bend: $100
Square holes: $40/plate (x 7 = $280)

Chroming will make it look shiny/pretty, bronze will not corrode, that is why I chose it over SS. However, it will tarnish and that's ok with me; it's a chainplate, not jewelry.

If you use carriage bolts, the machine shop will likely ask you for a bolt so they can make sure they cut the correct size hole. For me that caused a 2 week delay because I didn't buy the bolts until after I identified a machine shop that could cut the square holes.

Got the carriage bolts (1/2" carriage bolts) from Ron at Top Notch Fasteners (800 992-5151). They are custom made so the non-threaded part equals the thickness of the chain plate + hull + backing plate. I didn't want any threaded part to be on the bearing surfaces. The price was about the same as non-custom made (somewhere around $10 or $12 each, don't remember exactly)

[BAD ORCA]

For future reference, water jet cutting services should be able to easily cut out the profile and cut out all the holes, including the square ones fairly inexpensively. I use one thats going to cut my 1/4" stainless for keel bolt backing plates.

[Benz]

Originally Posted by alaskanviking

Thank you! That puts me on a path forward.

So you ordered the bronze

Took it to a shop to cut and bend the sheet

Took them to another shop to cut/punch the square holes

Then you ground the end round, drilled the pin hole, and sanded/polished yourself.

Your plates are fairly similar to mine. How much did the bronze/bending/punching cost?

I was thinking of sending them to get chromed after. More corrosion resistance, and the turnbuckles are chromed bronze.

I would avoid chrome: bronze doesn't need protection from corrosion, and eventually the chrome will wear and flake and look like crap. Too bad they chrome turnbuckles: there's nothing wrong with natural bronze, and verdigris does in no way weaken or degrade the bronze.

[alaskanviking]

Originally Posted by scherzoja

Yes, you understood the sequence correctly. You might get lucky and find one shop that can cut, bend, and cut square holes.



I compared the price of carriage bolts vs hex bolts and the price difference was not that much greater or carriage bolts (about a $4 difference).



If you don't want carriage bolts, the bronze is easy to drill. Much easier than stainless. I had a problem with my bits grabbing into the bronze and jamming (sharp cobalt bit), which caused the chuck to spin in the drill press (Morse taper chuck). I used a not-too-sharp steel bit to remove the bite marks. Once the bit grabbed, I just switched to a steel bit and finished the hole.



I also used Skene's table to calculate the location of the center for the clevis pin hole. It's not the center of the radius. There is a vertical offset that moves the hold center down a bit. See attached image. I also attached my drawing of the lower shroud chain plates to illustrate the offset. All my chain plates are 3/8" because I didn't want to buy different thicknesses of plate, so I made them all as thick as the backstay.





Bronze plate: $630 (incl shipping)

Cut and bend: $100

Square holes: $40/plate (x 7 = $280)



Chroming will make it look shiny/pretty, bronze will not corrode, that is why I chose it over SS. However, it will tarnish and that's ok with me; it's a chainplate, not jewelry.



If you use carriage bolts, the machine shop will likely ask you for a bolt so they can make sure they cut the correct size hole. For me that caused a 2 week delay because I didn't buy the bolts until after I identified a machine shop that could cut the square holes.



Got the carriage bolts (1/2" carriage bolts) from Ron at Top Notch Fasteners (800 992-5151). They are custom made so the non-threaded part equals the thickness of the chain plate + hull + backing plate. I didn't want any threaded part to be on the bearing surfaces. The price was about the same as non-custom made (somewhere around $10 or $12 each, don't remember exactly)

That actually helps a lot. I talked to a machine shop today that's doing some other work for me, sounds like they can do the bending. I'll know for sure tomorrow when I pick up my conduit.

Your plates are very similar to mine, so it's a big help figuring things out. I was almost desperate enough for stainless, just to get it done. Thankfully I'm busy enough with the mast that I didn't have to pull the trigger on anything yet.

2 years ago I converted from glassed in chain plates to bolt in, in San Diego. Crappy experience with the yard and contractor, but ultimately It led to reusing the old chain plates temporarily before I trucked the boat to Virginia. Big plus with that arrangement is they drilled the holes in the old plates, so they are good for templates. They installed the plates in the original position, just inboard of the toe rails. I had them make sister plates for the outside of the hull to spread the load. All hex bolts, but I'm leaning towards changing to carriage bolts now.

I don't like the vertigris so much. Makes me want to polish, and I've had my full of that. The nickle plating prior to chrome plate makes for even more corrosion resistance. Not that bronze really needs it. I can accept replating 20 years or so later, I guess. The old turnbuckles made it 30+ and still look halfway decent, I replaced a few. That's probably just a subconscious excuse. I think maybe I just like the shiny and I need to finally admit it. Very conflicted after finding out stainless is so poor for marine fittings lol.

[Cyrus Safdari]

Bronze is superior to 316 stainless for chainplates in many ways, mainly: relatively much less prone to crevice corrosion, however bending cast bronze depends on the specific alloy used. Silicon bronze is softer,which is why it is often used as rudder bearing and so can be bent easily (and unbent) but some of the bronze bar stock available online is aluminum bronze which cannot be bent much before it cracks ( tried it myself) much more brittle I am replacing all my shroud chainplates with aluminum bronze using bronze bolts and will glass them over too, without concern about causing crevice corrosion as would happen with 316 stainless, becuase they are either straight or require only minor bend but the chainplates for the forestry and backstay are thicker stainless 316 and so no glassedin. Using shouldered bolts is standard practice, also the threads shouldnt be in shear. Square holes are considered to create pressure points.

[scherzoja]

The chain plates are finally installed (been that way for a month or two). Of course, they are not as shinny, but I expected that.

Thank y'all for the advice to help me get his task finished. In retrospect, I probably should have made the upper shroud chain plates a few inches longer, but that is purely for aesthetic reasons.

Backing plates are 1/4" stainless steel that also tie into the original bulkheads/knees that were used for the original chain plates, bolts have no threads on the bearing surfaces, and I filled in gaps between the hull and chain plates with gel coated fiberglass.

On to other projects.

Thanks again for the help.

[Num1fireman]

Refitting an Classic 45ft Masthead Sloop rigged heavy cruising boat. wanted to replace the inboard 304 Chainplates with Bronze. Nothing obviously wrong with them other than being 48 years old since they come out through the side of the boat destroying the paint/gelcoat.

I bought 4 3 ft sections of 1/2 inch 954 bronze from McMaster-carr, enough for the 7 I need and 1 screwup...So I took the raw metal and my chainplates to a local plasma/waterjet cutting co. They have a Big shop, they are making a life sized bronze banyan tree for a state park when I dropped off the material. Although not something he does regularly , the owner, assured me he could do the work. I asked him to make one chainplate so that I could see the finished product before making the other 7.

He did, and failed to account for the hole stretch egging the rigging had done to the plate, and just copied the oblong hole... I gave him a clevis pin and corrected the mistake, otherwise they plate looked fine, it was bent at the correct angle and the mounting holes were correct. So I told him to proceed with the rest.

I tell him that I want to ship the plates to another company in Daytona, that would anneal and polish. He sends me an invoice with shipping and says he will ship after he gets paid.. which sounds fine to me, I pay the invoice, and 15 min later he sends me a picture of my chainplates that are all cracked at the bends because he cold bent them AFTER HE got paid.. Now Im out $1600 between material and his fee for paperweights... and I still don't have chainplates which is keeping me from painting the hull, which has to be done before the end of march before the humidity and rainy season start everyday cuz its a DIY paint job outside..

I want to go beat him to death with the bronze, but I think I will just sue him in small claims.. Im a 100% Disabled vet and that is a lot of $$ to me..

I am looking at just ordering 316 stainless flat bar and making them myself, since I can get it for around $600 and add an assload of time to make them myself, but really don't want to...

Any OTHER suggestions by the group would be appreciated..

[markxengineerin]

Have you asked for your money back? Usual case with something like this would be for you to lose the material, shop to lose their time. I have had my share of "new to me" shops screw up expensive parts, and this is the way it generally plays out.

From their perspective, you provided the material, gave them a verbal description of what you wanted, no drawings, may or may not have mentioned anything about cold bending. I assume there was no contract, and they gave it a "best effort" attempt which was a poor effort, but maybe these aren't the most expensive and capable workers.

Edit: Another idea might be to ask them to replace the parts in stainless, if you buy materials again. More productive compromise than court, where nobody wins.

[Ryban]

Originally Posted by Num1fireman

I tell him that I want to ship the plates to another company in Daytona, that would anneal and polish. He sends me an invoice with shipping and says he will ship after he gets paid.. which sounds fine to me, I pay the invoice, and 15 min later he sends me a picture of my chainplates that are all cracked at the bends because he cold bent them AFTER HE got paid.. Now Im out $1600 between material and his fee for paperweights... and I still don't have chainplates which is keeping me from painting the hull, which has to be done before the end of march before the humidity and rainy season start everyday cuz its a DIY paint job outside..

It's interesting that the bronze fractured -- I wonder if it was work hardened in the cold milling process that created your bar stock. What he probably should have done is heated and quenced the metal to anneal it and make it more ductile.

It's also strange that a reputable machinist would keep the money after making such a blunder. Did you make any attempts to recover your payment already? What did he say about the fractures?

[markxengineerin]

This is an extreme case, with the cracks, but what if the parts had been unsatisfactory for a different, more debatable reason? This is why drawings, purchase orders are used- to prevent miscommunication. Perhaps the shop is not qualified (or was not asked) to judge the properties of the supplied material or the suitability of the bending process, but undertook the job on a best effort basis. This is not unusual with a random job for a new customer, and a lot of times it's the best one can hope for as a random asking for something "custom".

There is no excuse for the individual worker not stopping and asking for advice after he bent the first one after he (should have) noticed cracks, except for the fact that he might be paid minimum wage, does not know, and does not care.

[Benz]

Should have been 651 bronze: that can take the bends, especially if not previously work hardened.
I'm sorry this happened to you, though--I think the shop should try and help you cut your loss.
Bummer.

[off-piste]

Originally Posted by scherzoja

Thanks to y'all for steering me away from cast chain plates. It's been a while, but I found a supplier for 3/8" bronze plate (4 weeks for delivery), then found a place to cut and bend (7 weeks for them to finally get around to getting the job done, then another machine shop to cut the square holes (another 6 weeks).

Then it took me about a week to drill the round holes for clevis pins, round off the ends, and clean up the finished product. That's the way it is around here. If I can find someone to do the work, it takes weeks for them to get the job done. Sometimes, after delaying for weeks, they come back and say, they can't do the job after all.

Oh well. These are done and now I have to install them and watch them tarnish.

Thanks again for the tips.

Sounds like it took as long as Port Townsend would have Hope it was cheaper?

[Bowdrie]

Originally Posted by Cyrus Safdari

however bending cast bronze depends on the specific alloy used. Silicon bronze is softer,which is why it is often used as rudder bearing and so can be bent easily (and unbent) but some of the bronze bar stock available online is aluminum bronze which cannot be bent much before it cracks

The above post is from a year or so back and is correct.
The 954 is an Aluminum Bronze and is NOT suitable for much in the way of bending.
The 655 Silicon Bronze is much to be desired if any bending is to be done.